Devices that have removable battery packs, such as laptop computers, personal audio and video players, etc., most often have two power input jacks. The first power-input port is obvious . . . it is where the connector from the external wall adapter, AC/DC power-conversion adapter, DC/DC automotive cigarette-lighter adapter, external battery charger, etc., is plugged in.
The second power-input port is not so obvious . . . it is where a removable battery pack connects to its associated host device. Usually, this is a power (or mixed-signal power and data) connector hidden in a battery bay, or expressed as a cord and connector inside a battery compartment, such as is found in some cordless phones. The connector between a battery pack and its associated host device may simply be a group of spring contacts and a mating set of contact pads. This second power port is not used for external power (a host's removable battery power source is usually not classified as “external” power). The battery power port is so unrecognized that even supplemental external “extended run-time” battery packs, as are available from companies like Portable Energy Products, Inc. (Scotts Valley, Calif.), connect to the same traditional power jack to which the external power supply does.
The connector assembly herein exploits this unutilized battery-to-host interface in a number of ways. As will be seen, a battery pack's power port is, in many ways, a far more logical power interface than the traditional power-input jack. By using a flexible and scaleable connector that is small enough to be enclosed within a battery pack housing, and providing sufficient connector contacts to handle power, the usefulness of external power devices and the battery pack itself can be enhanced.
Also, “smart” battery packs support connectors that are mixed signal, i.e., both power and data, therefore external power devices can data communicate with host devices and “smart” batteries, often facilitating device configuration, operation, and power monitoring.
Some of the reasons why the battery-contact interface isn't used are that it's often inaccessible. In laptop computers, for example, the battery-to-host-device connector is often buried deep in a battery bay. The connector assembly described in this document is built into the battery pack itself, at a location where easy access to a connector is available. Where appropriate, conductors from a non-removable battery are routed to an accessible location on the host device. Even when the location of the connector assembly is remote from the battery pack, the interface addressed is that between the battery pack and its associated connector on the host device.
Another reason for the lack of attention to the battery's power connector is that the type of connector used between a battery and its host device is not usually of the design and style that would easily lend itself to being attached to the end of a power cord. A good example of how awkward such battery access connectors can be is the “empty” battery housing with power cord that is popular with camcorders. The camcorder's “faux” battery pack shell snaps into the normal battery pack mount, and there is usually a hardwired cord to a power-conversion adapter. This makes for a considerable amount of bulky goods to transport. That is the case with cellular phones, as well, with “empty” battery housings that plug into an automotive cigarette lighter, or a battery pack with an integrated charger.
These are often bulkier than the battery pack they replace and, almost always, one must have a unique assembly—complete with cords—dedicated to a specific make or model of cellular phone.
The connector assemblies shown in the various figures, and described herein, are designed to be of the look and style normally associated with power and or data cords. Segmented-pin-type connectors are a common style. By defining new pin-style connectors that feature segmented receptacle contacts, or using segmented pin connectors in wiring schemes that create new connectivity paths, hitherto unknown ways of dealing with safety through power sub-system configurations are achieved. No bulky external add-ons are used. Instead, miniaturized connectors that can be embedded within an existing battery pack define new ways of powering battery-powered devices.
The battery packs discussed here are not empty battery enclosures, with only passthrough wiring. The original battery cells, circuit boards, fuses, etc., are all present and the connectors shown herein provide means to have a battery pack operate normally when a plug is removed (or replaced).
Battery Pack Removal
Another reason a battery port connector is not used is that to access this unexploited power port would require removing the battery pack, which would result in the loss of available battery power. Some host devices require that a battery pack be present, as the battery may be serial-wired. Also, host devices are known that use the battery pack as a “bridge” battery that keeps CMOS, clocks, etc., functioning. Battery removal could negatively impact such devices. Removing a battery pack also results in even more bulky things to carry around, which hardly fits the travel needs of someone carrying a laptop or other mobile device.
By embedding connectors in the battery pack, no circuits are created within the host devices. This is useful because battery packs are virtually always removable and replaceable. Instead of having to pre-plan and design-in new power and/or data paths into a host device, the replaceable battery pack contains these new electrical paths. Simply replacing a removable battery pack upgrades any host device. By placing the technology in a fully-functional battery pack, it is not necessary to remove the battery pack during connector assembly operations . . . instead, keeping the battery pack in its host device, where it belongs, is essential.
Devices that use external power-conversion adapters invariably are designed to always charge the device's battery pack every time the external adapter is attached. It seems logical that keeping battery capacity at 100% is a sound practice. However, certain rechargeable battery chemistries don't offer the charge/recharge cycle life that was available with “older” battery technologies. Lithium-Ion (Li-Ion) batteries, for example, can last for only 300 cycles, and sometimes even less than that. In average use, an Li-Ion battery can have a useful life (full run-time, as a function of capacity) of less than a year, and nine months isn't uncommon. Constantly “topping-off” a Li-Ion battery only degrades useful battery life.
Being able to elect when to charge the battery, independent of powering the host device, will prolong the life of expensive batteries. By delivering power from external power adapters and chargers through connectors at a newly-defined battery power I/O port, a user need only perform a simple act, such as inserting a plug specific to a battery-charging mode, or a host-power-only mode, or both.
Battery Charging Risks
Battery charging is a destructive process in other ways than repeated unnecessary battery charging sessions. Low-impedance batteries, such as Li-Ion, generate heat during the charging process. This is especially true if a cell-voltage imbalance occurs because, as cell resistance increases while charging, the entire battery pack has been known to overheat. Li-Ion cells have a reputation for volatility. For example, an article in the Apr. 2, 1998, edition of The Wall Street Journal reported on the potentials of fire, smoke and possible explosion of Li-Ion batteries on commercial aircraft (Andy Pasztor, “Is Recharging Laptop in Flight a Safety Risk?”, The Wall Street Journal, Apr. 2, 1998, pp. B1, B12).
To be able to easily disengage a volatile battery cell cluster from its integrated, hardwired battery charging circuit has obvious safety benefits. The connector assemblies discussed herein lend themselves to a simple battery bypass circuit within the battery pack, so that a host device can be powered from an external power source such as an aircraft seat-power system, without charging the battery. This function is achievable by simply replacing an existing battery pack with one that incorporates the subject connector assembly. This is a cost-effective, simple and convenient solution to an important safety concern.
The heat dissipation from charging a Li-Ion battery pack is compounded by the heat being generated by advanced high-speed CPUs. With computer processors running so hot in portable devices that heat sinks, fans, heat pipes, etc., are required, the additional heat from charging a battery only intensifies the thermal issues.
The connector assembly described herein, by disengaging battery charging, extends the life of a host device's components and circuits that otherwise may be compromised or stressed by extended hours of exposure to heat. This is especially valid for host devices such as laptop computers, since a number of these products are not used for travel, but instead spend almost all of their useful lives serving as a desktop substitute, permanently plugged into the AC/DC wall adapter in a home or office. In such device applications, the need to repeatedly charge the laptop's battery has no practicality. By using a connector assembly that can be selectively put into a mode for battery charging only when necessary, the working life expectancy of these host devices can be extended by eliminating unnecessary overheating.
Because the connector assembly is a modification to an existing battery pack, and battery products already have a well-established and wide distribution network, availability of this safety device is widespread. No entirely new devices are required to be designed and fabricated, since the connector assembly is essentially an upgrade modification.
Power-Conversion Adapters
Battery flammability and explosive volatility are related to inappropriate power devices in circuits upstream of the battery pack. Connecting an AC/DC power-conversion adapter that has an output voltage not matched to the input voltage of a host device is an easy mistake to make. Laptop computer input voltages, for example, can range from 7.2 VDC, to 24 VDC. Within that voltage range are a significant number of AC/DC and DC/DC power-conversion adapters that are connector-fit compatible, but which output incompatible voltages. A count of notebook computer power-conversion adapters available from one mail order company numbered over 250 discrete products (iGo, Reno, Nev., www.iGoCorp.com). The probability of a voltage mismatch indicates a serious safety concern.
As will be addressed in more detail later, to further exacerbate this plethora of power supplies problem, there are some 42 different types of existing laptop power connectors attached randomly to these 200+ power adapters. The connector assembly described herein also solves this connector mismatch issue.
Compared to the multiplicity of vast and diverse input voltages battery-powered host devices require when connecting to the device's power input jack, input voltages at battery power I/O ports are not only limited, but more input-voltage tolerant. Since battery output voltages are a function of an individual cell voltage, multiplied by the number of cells wired in series or parallel, there are a limited number of output voltages for battery packs. For example, Li-Ion cylindrical cells are manufactured at only 3.6-volts (some are 4.2-volt cells). Thus, virtually every Li-Ion battery pack made outputs either 10.8-volts, or 14.4-volts (with some relatively rare 12.6-volt cell clusters). If an external power-conversion adapter was designed to provide power to a notebook computer host device through the host device's battery power I/O port (instead of at the power input jack), it is possible that only two output voltages would be required, since the external adapter would electrically “behave” as a battery pack to a host device.
Furthermore, battery output voltages vary as a function of charge state. A fully charged battery—rated at 10.8-volts—actually outputs voltages in a range from about 10-volts, through 14.0-volts (with transient voltages up to 16 volts), depending on the battery's state of charge or discharge. So, by delivering power to a host device at its battery-to-host I/O port, a wide range of acceptable voltages is available. This same host device usually only will accept input voltages at its power-adapter input jack within a narrow voltage tolerance range of +/−1-volt. Thus, delivering power to a host device at its battery I/O port provides a far greater safety tolerance for potential voltage mismatches, as compared to power delivery at the traditional power jack. Also, providing a power connector that uses the battery's power I/O port, significantly reduces the number of external power devices, and the overall risk of damaging a host device by a voltage mismatch is minimized almost to insignificance.
Energy Conservation
There's a less obvious reason than safety to not charge batteries on commercial aircraft. Some commercial aircraft provide power outlets at the passenger seat. The headend of this “seat-power” system is a generator, so the total amount of energy to power all of the power outlets is limited. The Airbus A319, for example, has only sufficient generator capacity to provide “seat-power” for less than 40 passengers' laptop computers (Airbus Service Information Letter (SIL), dated 8 Jan. 1999). A laptop computer being powered from a power-conversion adapter connected at its power I/O jack uses 20-40% of the power to charge its battery pack, which translates to about 15-30 Watts per device. Generating sufficient power to charge 200+ laptop batteries puts a considerable drain on the aircraft's generator-driven electrical system.
Disabling battery charging by employing a connector assembly described herein is a cost-effective means of lowering an airline's operating costs, by minimizing the total load schedule of the cabin power grid. The airline saves the cost of the fuel required to operate the generator at a higher power capacity.
Another related issue is that airline operators have policies and in-flight rules that prohibit the types of passenger electronic devices that can legally operate on the plane. The use of RF devices, such as cellular phones, and radio-controlled toys, is banned on most every commercial aircraft. Passengers may be confused on aircraft operated by American Airlines, for example, since selected passenger seats have power systems for laptop use. This airline's seat power outlet is a standard automotive cigarette-lighter receptacle, just like the one in an automobile. An unsuspecting passenger, mistakenly assuming that the cigarette-lighter receptacle is for cellular phones, could easily plug in and turn on a cell phone.
Because there are a number of modalities to the connector assembly described in this document, airlines can elect to use a specific dedicated receptacle configuration, or wiring scheme that is reserved for passenger seat-power. By limiting the use of such a receptacle at passenger seats to laptops, and not allowing the seat receptacle to be used for cellular phones, an airline operator controls the types of passenger devices it allows to be connected to its cabin power system.
Battery-Only-Powered Devices
There is also a variety of battery-powered devices that does not have a power input jack. Cordless power tools, flashlights, and other devices meant to run strictly on removable, and/or externally rechargeable, batteries are typically not manufactured to accept an alternative source of power. If the battery of a cordless drill goes dead, the only recourse is to remove the battery and recharge it in its external charger. This is frustrating to a user who has to stop in the middle of a project to wait for a battery to recharge.
By integrating a new connector assembly, such as the ones shown in the figures and text herein, circuits can be created that use a host device's battery-power-port interface as a power connection through which an external power source delivers power. A user can elect, when a power outlet is available, to operate devices such as battery-powered drills, saws, flashlights, etc., from external power, simply by attaching a power adapter into a receptacle exposed on an accessible face of the device's battery pack. With some modalities of the connector assembly of the present invention, an external charger can be connected along with a power supply as well, allowing simultaneous equipment use and battery charging in electrical products that hitherto did not have these capabilities.
Devices with holders for individual replaceable primary battery cells fall into this same category of not having an external power I/O port. If the device does have an external port, it is usually not wired to provide simultaneous battery charging but only delivers power to the device. Not being able to charge replaceable battery cells in a battery holder while the batteries are in the host device lessens the usefulness of rechargeable alkaline cells, for example.
Charging peripherals for individually replaceable battery cells requires removing the cells from the device's battery holder. It is more convenient to leave these cells in their battery holder while charging, and the connector assembly discussed herein provides that convenience. The added convenience of being able to operate a host device instead of draining its rechargeable alkalines (these battery types typically can only be recharged 10-20 times, then must be discarded), reduces device operating costs. The use of the connector assembly herein also saves time, since the user doesn't have to take the time to turn off the device, remove each individual cell, place it in a special charger, then replace all the cells back in the holder.
Operational Advantages
Given the above, a number of operational advantages of the connector assembly of the subject invention become apparent:                (a). A simple, low-cost connector can be used to electrically isolate two previously coupled devices, such as a host device and its battery.        (b). By isolating the battery source, or a peripheral, from the host device, new circuits are created that enable a multiplicity of peripherals (e.g., external power sources, battery chargers, monitoring devices, external batteries, etc.) to be used. These add-on peripherals also operate more safely, because the battery voltage can be verified before the external peripheral is turned on.        (c). Because a plug is configurable to create additional circuits that were previously unavailable, specialty functions or operations will now be performed at the battery and/or host device.        (d). A variety of uniquely configured plugs can be interchanged, thus affording selective access to electronic and electrical devices.        (e). With its very small form factor, a receptacle is embedded inside a battery pack, to make it a self-contained device that has a special power (and/or data) interface to external power, charging, or monitoring peripherals. This can be accomplished without having to rewire or otherwise modify a host device. By replacing the existing battery pack with one configured with a connector assembly herein, the functionality of both a previously unknown battery and its host device is enhanced, without permanent reconfigurations to either the battery pack or host device.        (f). The connector assembly can be used as a replacement for an existing input power jack, with minimal modifications or rewiring.        (g). Problems with the existing multiplicity of connectors on electronic devices that allow incompatible external adapter output voltages are eliminated. Instead, the receptacle is simply wired in a different configuration, and a distinctive plug is used to differentiate the two incompatible external adapters. Any fear of possible mismatched voltages between external power adapters and host devices is eliminated.        (h). This embodiment of the connector assembly uses an insertable “jumpered” terminator plug to reinstate a circuit, so the need for an ON/OFF power switch in conjunction with a power input jack is eliminated. The terminator plug is configurable to turn the host device ON when the plug is inserted into a receptacle.        (i). The plug and receptacle of the connector assembly provide a retention mechanism that secures the mated assembly—an important feature for devices like laptops that are often moved around the local area in industrial or service applications.        (j). In certain high-risk environments, host devices that automatically charge their batteries when external power is applied can be easily modified by inserting a battery pack that has been upgraded to the connector assembly. Thus configured, the battery does not charge, and thus powering the host device is rendered safety compliant.        (k). Simultaneous battery monitoring and power delivery from an external peripheral is achieved without modifying the internal circuitry of the host device.        (l). By installing a means of controlling the direction of signal flow, e.g., a switch that responds to applied power signals, a diode, etc., located at either the plug or receptacle of the connector, battery monitoring and power delivery can occur with a two-conductor cable.        (m). Monitoring battery charging is performed by an external device attached to a connector assembly as defined herein, which is further capable of power delivery, data transfers (or both).Applications        
A battery pack upgraded with the subject receptacle creates new electrical paths for power and/or data when a configurable plug is inserted (or removed) enabling applications such as (but not limited to) the following:    1) Diminish excessive and unnecessary charging of a battery when attaching an external power source. By not charging a battery every time a host device is connected to an external source of power, the life expectancy of the battery is increased. Since most rechargeable battery-powered electronic devices automatically charge their batteries when external power is connected, the use of a connector assembly that disables the battery charge function increases the useful life of the battery, thus reducing total operating cost.    2) Some applications may not find battery charging practical. Battery charging can consume 20-40% of the entire load schedule of a host device's available power. If a car's battery is low, operating a host device such as a laptop for an extended time from the dashboard outlet could result in a stranded motorist.    3) Some transportation locations may not allow for battery charging. There is risk in charging batteries, especially high-density Li-Ion cells. An airline or cruise ship operator, for example, may wish to limit the risk of an onboard battery-related fire or explosion. A simple and cost effective method is to deploy battery packs and power cords that have a connector assembly which disables the charge function, while still allowing an external power supply to power the host device.    4) Extended-run-time external battery packs can be used to supplement a host-device's associated battery. These extra-high-capacity battery packs connect to a host device's existing power-input jack. So configured, the external battery pack dedicates some of its stored energy to charging the host device's battery. This occurs because host systems are designed to charge the associated battery whenever external power is available. As a power source, a host device usually does not distinguish an external battery from an AC/DC wall adapter, so the extended-run-time battery loses its effectiveness by having to relinquish some amount of its stored energy to charging the host's battery. By using a connector as described herein, the extended battery routes its power along a new circuit which bypasses the host device's existing battery pack. By doing so, the charging circuits within the host device are temporarily disabled while the external battery source is in use. This enhances the run-time of the external battery, and also eliminates inefficient energy transfers between the two batteries.
These non-limiting examples of applications for connector assemblies such as those described in this document thus show some practical real-world uses.
Design Parameters
Some of the connector design parameters required to achieve the above-defined applications are:    1) Small package size, especially for the receptacle, since available space within battery packs is limited.    2) Straightforward method of integrating a receptacle into an existing battery pack, or for installing the receptacle in a new battery pack design in a way that doesn't require an inordinate amount of extra tooling or assembly.    3) Inexpensive    4) Simplicity of use